The human body also contains potassium. If a 70-kg person has an average of 140 g potassium in his or her body, what is the radioactivity of this person, in becquerel, coming from 40K? See Exercise 21.63 for necessary data.

Exercise 21.63

Natural potassium is 0.0117% radioactive 40K, which decays by positron emission with a half-life of 1.26 × 10⁹ years. If an average banana has 6.00 × 10^-1 g potassium in it, what is the radioactivity of a banana in becquerels?